Leinster remain on course for back-to-back Heineken Cup titles after seeing off Clermont Auvergne 19-15 in a thrilling semi-final clash at the Stade Chaban Delmas in Bordeaux on Sunday.

The Irish side produced a superb second-half display of game-breaking invention and resolute defence to deny their French rivals a first-ever final appearance and set up a showdown with their provincial neighbours Ulster at Twickenham on May 19.

It was heart-breaking for Clermont, who had led at the break thanks to four penalties from fly-half Brock James, with his opposite number Jonathan Sexton keeping a second-best Leinster in touch. The game swung the defending champions' way after the break with a try from prop Cian Healy and an outrageous drop goal from fullback Rob Kearney steering them into a deserved lead.

Back came Clermont and they thought they had rescued the game when centre Wesley Fofana crossed in the closing moments, but his score was ruled out by the Television Match Official and Leinster dug deep to keep their own euro dreams alive.

With Sexton pulling the strings, Leinster made the first telling incision as winger Isa Nacewa exploited a sliver of space down the line and the result was the opening score of the game courtesy of his fly-half.

An audacious drop goal attempt from James would soon sail wide of the posts and there was more cause for concern a few moments later after a chip and chase from Nacewa had Clermont stretched. But they soaked up the pressure and hit back with a penalty from James that appeared to send confidence rushing through their veins and only a marginally forward pass on the Leinster 22 prevented them from turning the screw.

Given the intensity of an occasion billed as the 'most exciting clash of the season', it was a little surprising that we had to wait until midway through the half for tempers to boil over and Leinster lock Leo Cullen was lucky to escape sanction for a half-hearted punch, although the dive from Clermont prop Lionel Faure was equally unwelcome.

Despite being stripped of two of their starting back three, with Julien Malzieu and then Lee Byrne removed by injury, Clermont retained a cutting edge with some excellent handling asking serious questions of the Leinster defence. They stood firm but their eagerness to snuff out the danger gifted James his second penalty of the afternoon. However, Clermont immediately undid much of their good work with the otherwise impressive powerhouse winger Sitiveni Sivivatu taking out Nacewa in a reckless act that allowed Sexton to level things up once more.

But it was not enough to shift the momentum and the tit-for-tat exchange would continue just a minute later with James slotting his third penalty after Healy was penalized for going off his feet at the breakdown. The loose-head was at fault again before the break with a wild offload handing Clermont great field position from where their pack earned yet another penalty that James slotted to give his side a six-point cushion at the break.

With their proud Heinken Cup record, which now stands at 14 games unbeaten, on the line, Leinster exploded out of the blocks at the start of the second-half to blow the game wide open. A simple inside ball from hooker Richardt Strauss to fullback Rob Kearney split the Clermont defence and Healy went from zero to hero by taking the scoring pass. Sexton's conversion gave Leinster the lead and lit the fuse on what would be an electric second period.

Not content with cutting a swathe through the Clermont defence, Kearney then cemented his side's advantage, and his claims for the Man of the Match honour, with a monster drop goal sailing through the posts. James' attempt to replicate the feat a minute or so later was short and wide but not as ugly as his next penalty kick - the first missed on semi-final weekend. Thankfully for the vociferous Clermont supporters he rediscovered his scoring touch when opportunity next knocked.

Leinster's penalty count continued to frustrate Clermont and referee Wayne Barnes who issued a warning to skipper Cullen but his side had no intention of taking a step back. The energy of replacement scrum-half Eoin Reddan sparked another telling turnover and a step from centre Brian O'Driscoll led to Sexton's latest success from the kicking tee.

A strong run from flanker Sean O'Brien threatened to put the result beyond doubt before his adventure got the better of him and there was a further flicker of hope for Clermont when the otherwise perfect Sexton pushed his next penalty attempt wide - with the TMO called upon to confirm the miss.

With Clermont appearing to run out of steam, Sexton was happy to play for territory the nature of the game had clearly taken its toll on Leinster too. Clermont took heart and time and time again they thundered into the Leinster defence, edging nearer and nearer the line on each occasion. With the crowd roaring them on, Fofana crashed through to touch down but his celebration was premature, with TMO Geoff Warren ruling correctly that he lost control of the ball in the process.

The resulting scrum handed them one last chance to rescue the result and a monumental effort earned them a priceless penalty. The forwards attacked the line with renewed vigour and following another penalty, one final surge took them to within inches. But there would be no way through, with Leinster snuffing out the move to book their passage into yet another final.